In recent years, with the spread of information terminals for individuals represented by smartphones and the like, an amount of information in which each individual receives is increasing. In such information terminals, a plurality of applications usually operate in an asynchronous manner to transmit information irregularly and frequently.
The information transmitted from the information terminal itself or the application executed in the information terminal includes visual information such as image information or character information. In such cases, the image information or the character information is provided to a user by being displayed as images or characters on a display provided in the main body of the information terminal or an external display terminal connected to the information terminal. PTL 1 discloses an eyeglass-type image information display terminal as an example of such information terminal.
However, in the image information display terminal that displays transmitted notification information as an image disclosed in PTL 1, there is a problem that a certain labor occurs for a user, such as necessity of interrupting work which has been performed just before, in order for the user to gaze at an image displayed on an image display unit such as a display.
On the other hand, the information transmitted from the information terminal or the application also includes an auditory situation such as sound information. In such case, the sound information is provided to a user by being output as sound in a stereo form, a stereophonic sound form, or the like through a speaker provided in the information terminal, or a headphone or an earphone connected to the information terminal. Therefore, it is considered that notification of information to the user is performed not by displaying the images or the characters, but by outputting the sound in order to avoid the interruption of the work of the user. PTL 2 discloses a stereophonic sound control device that provides an indication of a direction to a listener with a sound.